Home prices rose in two thirds of U.S. metropolitan areas in the second quarter as the expiration of tax credit spurred home sales, the National Association of Realtors said Wednesday.

The median price for resales of single-family homes increased in 100 of the 155 metropolitan areas tracked by the trade group. Housing analysts have warned that the home-price trend could prove fleeting if a faltering economy saps demand and if the pace of foreclosures increases. (See a sortable list of home prices by metro area.)

The national median price for single-family homes rose to $176,900 in the second quarter, up 1.5% from one year earlier, as distressed sales accounted for a smaller share of home sales.

Metro areas that showed the biggest gains from a year earlier included Akron, Ohio (36%), San Jose, Calif. (26%), and San Bernardino, Calif. (18%). Those increases don’t necessarily correspond to rising values but instead show that the mix of sales has shifted away from foreclosures selling at fire-sale discounts. Metro areas that showed the biggest declines included Cumberland, Md. (down 15%), Tuscon, Ariz. (down 14%) and Ocala, Fla. (down 13%).

While many of California’s hard-hit housing markets have rallied over the past year, bubble markets in Florida have struggled. Wednesday’s report showed some bright spots—in the Fort Myers metro area, which has witnessed some of the heaviest overbuilding and unemployment, prices were up 12% from one year ago. But others continue to see values erode. Jacksonville and Daytona Beach posted median price declines of 9% and 8%, respectively.

The report looks at home sales in the April-to-June period, a period in which many home sales were eligible for tax credits worth up to $8,000. To qualify, buyers had to go under contract by April 30, and they have until next month to close.

Newly signed contracts plunged in May and haven’t rebounded, while inventories of unsold homes are rising. Analysts expect that sharp decline in sales to show up in this month’s report of home resales, and economists see home prices falling in the second half of the year.